Problem: Simplify the expression. $(5a-5)(3a+5)$
Explanation: First distribute the ${5a-5}$ onto the ${3a}$ and ${5}$ $ = {3a}({5a-5}) + {5}({5a-5})$ Then distribute the ${3a}.$ $ = ({3a} \times {5a}) + ({3a} \times {-5}) + {5}({5a-5})$ $ = 15a^{2} - 15a + {5}({5a-5})$ Then distribute the ${5}$ $ = 15a^{2} - 15a + ({5} \times {5a}) + ({5} \times {-5})$ $ = 15a^{2} - 15a + 25a - 25$ Finally, combine the $x$ terms. $ = 15a^{2} + 10a - 25$